R.C.
I went off the pill in January 2009, trying to help get me off blood pressure meds, and started FAM. We were very familiar with it, since we had used it to get pregnant in 2003. We were using condoms on my fertile days. I got pregnant in March :-0.
[He's a perfect little 12-month-old now, and I'm glad this method "failed" for us.]
I think it is a great way to get to know your physiology and avoid hormones, but unless you are able to very accurately chart (including temps--that messed me up because I have a weird work schedule), then it may not be effective.
I agree with above posters. An IUD is effective and nearly immediately reversible if you decide to have more kids.